JPH0289059A - Baking method - Google Patents

Abstract

PURPOSE:To form insulating films having stable film quality by sucking the air in a baking furnace into which material to be treated are put to increase the degree of vacuum and to evaporate the solvent of a photosensitive polyimide-based coating liquid and then heating up the circumference of the baking furnace by heaters upon lapse of the prescribed time thereafter. CONSTITUTION:The baking device is constituted of the baking furnace 3' which is constituted to generate a vacuum by sucking the air therein through a rotary pump 5 and a valve 6 and the heaters 4 provided around this baking furnace 3'. The air in the baking furnace 3 into which the materials 1 to be treated are put is sucked by the rotary pump 5 to increase the degree of vacuum and to evaporate the solvent of the photosensitive polyimide-based coating liquid (PiQ liquid); thereafter, the circumference of the baking furnace 3' is heated up by the heaters 4. The greater part of the solvent of the photosensitive PiQ liquid is, therefore, removed by evaporation and is then solidified by a thermal crosslinking reaction. The insulating films having the stable film quality is formed in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photosensitive polyimide coating solution (polyimide iso-indole mixed with a photosensitive organic substance) applied to the surface of a workpiece such as a wafer.・Cinchona silidione liquid,
Regarding the baking method of drying a photosensitive PiQ liquid (hereinafter abbreviated as "photosensitive PiQ liquid") to form an insulating film on the surface of a processed object, it is particularly concerned with the baking method of drying a photosensitive PiQ liquid (hereinafter abbreviated as "photosensitive PiQ liquid") and forming an insulating film with stable film quality by expelling the solvent of the photosensitive PiQ liquid and air bubbles in the solvent. Concerning a baking method that can produce .

[Conventional technology]

In the conventional baking method of this type, as shown in FIG. , and the area around the baking oven 3 is heated by heaters 4, 4 . The photosensitive PiQ liquid was dried by heating to raise the temperature to form an insulating film on the surface of the object 1 to be processed. At this time, the heaters 4, 4. As shown by curve a in Figure 5, the heating temperature increase curve for ... is such that heating is started gradually from the beginning of the treatment time and reaches a constant temperature, for example, about 400°C, after a predetermined time. Ta. At this time, when the temperature is raised to a certain temperature, the photosensitive PiQ liquid applied to the surface of the object to be processed 1 begins to solidify due to a thermal crosslinking reaction (amide is imidized and hardened when heated), and an insulating film is formed. [Problem to be solved by the invention] However, in such conventional baking methods, the fourth
As shown in the figure, the object to be processed 1 was placed in the baking furnace 3 and the temperature was simply heated, so even if the heating temperature was gradually increased at the beginning of the processing time as shown in For example, at about 145°C, the solvent of the photosensitive PiQ liquid starts to volatilize, and at about 165°C, the amide starts to imidize and harden, and the solvent volatilization shown by the curve in FIG. 6 and the solidification shown by curve C occur almost simultaneously. It was an ongoing process. Therefore, when the solvent evaporates from inside the photosensitive PiQ liquid applied to the surface of the object to be treated 1, the film has already begun to solidify on the surface of the photosensitive PiQ liquid due to the thermal crosslinking reaction. The solvent remaining under the membrane remained inside in the form of bubbles. In this case, the photosensitive PiQ liquid was not completely dried, and an insulating film with stable film quality was not produced.

If the film quality is not stable in this way, the adhesion between the substrate of the object to be processed 1 and the insulating film may deteriorate, making it easy to peel off.
Heat resistance may deteriorate due to air bubbles.

Or, the insulation of the wiring between the eyebrows may deteriorate, causing the product (I
In addition to resulting in defective products (electronic components such as C), the yield rate also decreased.

Therefore, one object of the present invention is to provide a baking method that can solve these problems.

[Means to solve the problem]

In order to achieve the above object, the baking method according to the present invention involves placing a workpiece whose surface is coated with a photosensitive polyimide coating liquid into a baking oven, heating the area around the baking oven with a heater, and raising the temperature. In the baking method, which dries the photosensitive polyimide coating solution by heating to form an insulating film on the surface of the object to be treated, the air in the baking oven containing the object to be treated is sucked to maintain the degree of vacuum. The solvent of the photosensitive polyimide coating liquid is evaporated, and after a predetermined period of time, the temperature around the baking oven is heated with a heater.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a graph showing the relationship between processing time, degree of vacuum, and heating temperature for explaining the baking method according to the present invention. As shown in FIG. 2, the baking apparatus to which this baking method is applied is a baking oven 3 which sucks internal air through a rotary pump 5 and a valve 6 to create a vacuum.
', a heater 4 provided around this baking oven 3',
4. It consists of... Then, a plurality of workpieces 1 such as wafers whose surfaces are coated with the photosensitive PiQ liquid are stacked in a cartridge 2 and put into a baking oven 3', and the area around the baking oven 3' is heated by a heater 4, 4. By heating and increasing the temperature, the photosensitive PiQ liquid is dried and an insulating film is formed on the surface of the object to be processed 10.

The baking method in such a baking device is as follows:
First, as shown by curve d in FIG. 1, air in the baking oven 3' containing the object 1 to be processed is sucked by the rotary pump 5 to increase the degree of vacuum and evaporate the solvent of the photosensitive PiQ liquid.
Thereafter, after a predetermined time t has elapsed, heaters 4, 4. Heating to raise the temperature.

At this time, by increasing only the degree of vacuum at the beginning of the processing time, as shown by curve d in Figure 1, only the volatilization of the solvent takes precedence at the beginning of the processing time, as shown by curve b' in Figure 3. 6, and rises with a stronger curve than the conventional solvent volatilization curve shown in FIG. At this time, the photosensitive P
Thermal crosslinking reaction has not yet started on the surface of the iQ liquid. As a result, the solvent of the photosensitive PiQ liquid evaporates more easily than under normal pressure, and air bubbles in the solvent also become easier to remove. Thereafter, when a predetermined time t has elapsed and most of the solvent of the photosensitive PiQ liquid has evaporated, the baking oven 3' is heated with heaters 4°4, . . . as shown by curve e in FIG. Raise the temperature to approximately 400°C. Then, the photosensitive PiQ liquid applied to the surface of the object to be treated 1 starts to solidify mainly after a certain period of time due to a thermal crosslinking reaction, as shown by curve C in FIG.

That is, as shown in FIG. 1, only the degree of vacuum in the bake oven 3' is increased at the beginning of the processing time (see curve d), and after the elapse of a predetermined time t, the temperature inside the bake oven 3' is increased (see curve d). (see e), photosensitive PiQ is formed as shown in Figure 3.
The volatilization of the liquid solvent (see curve b') and the assimilation by thermal crosslinking reaction (see curve C) are separated on the time axis of the treatment.

This prevents solvent volatilization and assimilation from proceeding simultaneously as in the conventional example shown in FIG.
After most of the solvent in the liquid is volatilized and removed, it is solidified by a thermal cross-linking reaction, and the photosensitive PiQ liquid can be completely dried to form an insulating film on the surface of the object to be treated.

〔Effect of the invention〕

Since the present invention is configured as described above, the volatilization of the solvent of the photosensitive PiQ liquid and the solidification of the insulating film due to the thermal crosslinking reaction can be separated on the processing time axis. Therefore, it is possible to prevent solvent volatilization and assimilation from proceeding simultaneously as in the past, and to solidify the insulating film by thermal crosslinking reaction after most of the solvent in the photosensitive PiQ liquid has been volatilized and removed. can.

Therefore, the solvent of the photosensitive PiQ liquid and the bubbles in the solvent can be almost completely expelled, and the photosensitive PiQ liquid can be completely dried to produce an insulating film with stable film quality. Therefore, it is possible to improve the adhesion between the base of the workpiece 1 and the insulating film, making it difficult to peel off, and to improve the insulation of the wiring between the eyebrows, thereby improving the quality of the product and the yield. In addition, in the beta method of the present invention, either batch processing or single-wafer processing can be applied to the object 1 to be processed.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between processing time, degree of vacuum, and heating temperature for explaining the baking method according to the present invention;
The figure is an explanatory diagram showing an overview of a baking device to which the baking method of the present invention is applied, FIG. 3 is a graph showing the processing profile of the present invention, and FIG. 4 is an overview of a baking device to which the conventional beta method is applied. FIG. 5 is a graph showing the relationship between processing time and heating temperature for explaining the conventional baking method, and FIG. 6 is a graph showing the conventional processing profile. 1... Workpiece, 2... Cartridge, 3
'... Bake oven, 4... Heater, 5...
Rotary pump, 6 valves. Applicant: Hitachi Electronics Engineering Co., Ltd. Hitachi, Ltd.

Claims (1)

[Claims] The object to be treated whose surface is coated with the photosensitive polyimide coating liquid is placed in a baking oven, and the area around the baking oven is heated with a heater to raise the temperature, thereby drying the photosensitive polyimide coating liquid. In the baking method in which an insulating film is formed on the surface of the object to be treated, the air in the baking oven containing the object to be treated is sucked to increase the degree of vacuum to evaporate the solvent of the photosensitive polyimide coating liquid, and then A baking method characterized in that after a predetermined period of time has elapsed, the area around the baking oven is heated with a heater to raise the temperature.